To obtain F.sub.1 hybrid seeds, which have advantages over non-hybrid seeds, seed breeders cross-pollinate carefully selected parent plants. Wheat plants have hermaphroditic flowers, and normally self-pollinate. This characteristic can cause a problem in effecting cross-breeding, leading to mixtures of hybrid and non-hybrid seed. The problem has been solved in the past by emasculating (removing the male anthers) each of the flowers of the prospective female parent plant by hand before it is pollinated by pollen from the prospective male parent. Such hand operations are extremely laborious and time-consuming, and require highly-skilled workers. Much research is being carried out with a view to effecting the emasculation by treating the prospective female parent with a chemical, and thus avoiding such hand operations.